COME and RAOM are inflammatory diseases of the middle ear. Biofilm formation may be a factor in the pathogenesis of COME, see Post, J.C., “Direct evidence of bacterial biofilms in otitis media”, Laryngoscope 111(12):2083-94 (2001), Ehrlich et al., “Mucosal Biofilm Formation on Middle-Ear Mucosa in the Chinchilla Model of Otitis Media”, JAMA 287(13): 1710-15 (2002) and Fergie, N et al., “Is otitis media with effusion a biofilm infection?”, Clin Otolaryngol Allied Sci. 29(1):38-46 (2004). Biofilms form when bacteria interact with a surface to form polymeric films (sometimes referred to as exopolysaccharide or extracellular polysaccharide polymers) that coat the surface and provide a living colony for further bacterial proliferation. Bacteria lodged in biofilms are much more difficult to remove or kill than bacteria in a plaktonic (suspended) state, and are extremely resistant to many antibiotics and biocides. Both the extracellular polysaccharide (EPS) matrix and the toxins produced by a number of different bacteria have been shown to cause inflammation by the host. It appears that the chronic inflammation associated with COME and RAOM is a host response to the bacterial biofilm.
COME and RAOM are usually initially treated using oral antibiotics and then, if need be, are more aggressively treated by placement of a tympanostomy tube. Occasionally in cases involving severe infection or high mucous content in the middle ear, the middle ear may be irrigated (e.g., with saline solution). While tympanostomy tubes work on most patients, about 20% of patients who undergo primary tympanostomy tube placement require an additional surgery (an adenoidectomy, a second set of tympanostomy tubes, and usually both an adenoidectomy and tympanostomy tube placement) to treat persistent COME or persistent RAOM.
Cholesteatoma is another ear disease condition of concern. Although generally thought to be primarily a cyst comprised of dermal cells, bacteria biofilms have also been implicated in this disease, see Chole et al., “Evidence for Biofilm Formation in Cholesteatomas”, Arch Otolaryngol Head Neck Surg. 128, pp. 1129-33 (October 2002). In cholesteatoma, bacterial biofilms appear to form, incite inflammation, and cause generation of a benign tumor composed mainly of bacteria at its core and dermal cells. The tumor can erode both the ossicular chain (hearing bones) and the mastoid bone, detrimentally affecting hearing. Surgical exposure and excision is the most common treatment for cholesteatoma removal. Up to 25% of these procedures fail due to recurrence of the cholesteatoma and thus require additional surgery or other treatment.
The etiology and chronicity of COME, RAOM and cholesteatoma appear to be related to the presence of bacterial biofilms as well as their recalcitrance post-surgery.